Renewing shrubs are plant species with branch architecture that can regenerate itself after severe pruning or damage by weather or accident. These tend to be deciduous shrubs, but some evergreens such as azaleas and yews can also renew themselves this way, according to Purdue University. Needle evergreens, such as junipers and pines, are not renewing. Pruning renewing shrubs involves removing old woody tissues on a stepped, three-year regimen; over three years, all of the shrub branches are removed and replaced with new growth. While this is not required pruning, it is a good way to achieve a fuller shrub, or to re-size and rejuvenate a long-neglected shrub.
Time your renewal pruning carefully to support desired flowering or fruiting performance in the shrub. Prune flowering shrubs immediately following bloom, unless you wish to have the berries, fruits or seed pods develop on the shrub. If fruiting is desired, prune in the early winter after the berries have matured and been consumed by wildlife. Prune foliage-only shrubs in the spring after the last frost, as well as flowering and fruiting varieties, if you do not care about preserving the ornamental display or food resource for wildlife.
Prune away up to 1/3 of the oldest branches and limbs in year one of the renewal process. Cut the branches down to the crown of the plant just above the soil line or to the main trunk. Distribute the pruning cuts evenly around the shrub to preserve its natural form.
Cut away another 1/3 of the oldest branches down to the crown or main trunk of the shrub in the second year.
Remove the final 1/3 of the oldest wood in the third year. Trim back the new growth that was generated by year one's renewal pruning, if needed to keep the shrub looking full and tidy.